Composite structures are being developed to replace aluminum components for use with space launch vehicles. Replacement of aluminum components with lighter, lower cost, and less thermally conductive composite components will enable larger payloads, reduced operating costs and longer missions due to propellant boil-off reduction.
In the construction of the composite structures, composite fluted core sandwich shell wall assemblies were employed. These wall assemblies were used, for example, in the construction of an external structural wall assembly of a rocket or in the construction of a cryogenic tank assembly. Sections of the wall assemblies were joined together with joint edge structures so as to connect adjoining sections of the structure being assembled. As higher line load demands are encountered and needed than originally used in smaller rockets or structures positioned higher in a stack, for example, an improved edge joint construction is needed for constructing the structural assembly with composite fluted core sandwich shell wall sections.
The lighter load shell edge joints originally developed required relatively large openings between intermittently spaced shell edge reinforcements to allow extraction of tooling. As a result of the relatively large openings, that construction did not permit more closely spaced fasteners that would be needed for a joint that needed to carry a higher load capacity. The lighter load shell edge joint construction also forced load into the face sheets of the structure at the ends of the flutes which necessitated positioning a local doubler for carrying higher loads for which the original joint was not designed.
An improved shell edge joint for a composite fluted core sandwich shell wall is needed and a method to assemble a composite wall assembly edge joint is needed that will provide improved load carrying capabilities such that more load can be carried and distributed permitting additional and more closely spaced fasteners. This improved shell edge joint performance for increased load capacity needs to be accomplished with minimizing the increase in vehicle weight.